diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/GC/regress-313276.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/GC/regress-313276.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 313276;
+var summary = 'Root strings';
+var actual = 'No Crash';
+var expect = 'No Crash';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+ 
+var obj = {
+  toString: function() {
+    return "*TEST*".substr(1, 4);
+  }
+};
+
+var TMP = 1e200;
+
+var likeZero = {
+  valueOf: function() {
+    if (typeof gc == "function") gc();
+    for (var i = 0; i != 40000; ++i) {
+      var tmp = 2 / TMP;
+      tmp = null;
+    }
+    return 0;
+  }
+}
+
+  expect = "TEST";
+actual = String.prototype.substr.call(obj, likeZero);
+
+printStatus("Substring length: "+actual.length);
+printStatus((expect === actual).toString());
+
+reportCompare(expect, actual, summary);